ACTG 393: Mycobacterium avium Complex (MAC) is a serious and sometimes life-threatening bacterial infection that usually only people with HIV infection can get. It is usually only found in HIV-infected people who have less than 50 CD4+ cells/mm3. (CD4+ cells are the infection-fighting white blood cells destroyed by the HIV virus). It is recommended that people who are likely to get MAC infection be placed on preventive medications (such as clarithromycin, azithromycin, ethambutol, and rifabutin) which help reduce the risk of MAC infection. We know that the new combination of anti-HIV drugs can result in higher CD4+ cell counts and can reduce the amount of HIV in the blood to amounts that cannot be measured. This study is for people who have had MAC before, been treated for at least 12 months and are now free of any signs of MAC for at least 16 weeks, and have CD4+ cells counts of greater or equal to 100 cells/mm3. The purpose of this study is to find out whether MAC preventive medications can be stopped in subjects who are currently receiving anti-HIV drugs without placing them at risk for MAC infections.